Fourier transform infrared spectroscopic characterization of clay minerals from rocks of Lalibela churches, Ethiopia

International Journal of Physical Sciences

Alemayehu Kiros¹ 

关键词: Fourier transform infrared (FTIR);    Raman;    whewellite;    kaolinite;    rock hewn churches;    mineral characterization.;   

DOI  :  10.5897/IJPS12.714

学科分类：物理（综合）

来源: Academic Journals

【 摘 要 】

This study demonstrates the Fourier transform infrared (FTIR),Raman spectroscopy andscanning electron microscope -energy dispersive X-ray spectrometer (SEM-EDS) techniques which has been applied to characterize decay products and processes occurring at the surface of rock-hewn churches at the UNESCO’s World Heritage site of Lalibela, Northern Ethiopia.Spectroscopic analyses comparing the observed frequencies with the available literature, minerals were identified. A special emphasis is devoted to the presence of whewellite/weddellite and kaolinite minerals, never pointed out before this study in the rock hewn churches of Lalibela, and their possible roles on rock decay. The identification of montmorillonite as a weathering product up to 20 mm from the rock/atmosphere interface beyond the level at which kaolinite, whewellite and gypsum are found, suggests that montmorillonite may penetrate even deeper into the rock substrate causing major rock decay.Results indicate that biological attack by green algae and lichens is currently responsible for severe stone surface, physical and chemical weathering leading to considerable weakening of the churches walls.A prompt and careful removal of the biological and other deposits with the non-destructive method (laser cleaning) treatment is therefore recommended.

【 授权许可】

CC BY